What is your noise floor?

[sdolezalek]

Given all the recent posts about what we can and cannot hear, I wondered what noise floor my system actually had to overcome in my listening room. When I'm in that room with the system turned off, it seems totally silent, but using the SPL Meter in Studio Six's AudioTools and the internal microphone in my iPhone tells me that my "silence" is actually a level of background noise in the high 20's dB's. That seemed incredibly noisy until I read that a quiet bedroom at night is generally in the 30's and the background level in a TV studio is 20dB or so.

 

Do you know what yours is and have you attempted to do anything to lower it?

[esldude]

Given all the recent posts about what we can and cannot hear, I wondered what noise floor my system actually had to overcome in my listening room. When I'm in that room with the system turned off, it seems totally silent, but using the SPL Meter in Studio Six's AudioTools and the internal microphone in my iPhone tells me that my "silence" is actually a level of background noise in the high 20's dB's. That seemed incredibly noisy until I read that a quiet bedroom at night is generally in the 30's and the background level in a TV studio is 20dB or so.

 

Do you know what yours is and have you attempted to do anything to lower it?

 

Excellent question to post.

 

Late at night I can get near 30 though typically more like 35 db. If you get an RTA type read out you can get an idea of which frequencies are the main contributors. Usually it will be lower frequencies, and low frequencies travel the furthest before dying out and are hardest to stop. One can often get 20db up around the 3-5 khz area where our ears are most sensitive. That is also an area where some sound absorbing materials work well.

 

Daytime numbers are more like mid 40's for me. And then there is the train. I live about .5 mile ( .8 km) from a railroad track. Those long trains can bump up the low frequencies a bunch. With a meter that responds to very low frequencies I can tell when they are about 5 miles away from getting nearest me. Then there are neighbor's leaf blowers, lawn mowers or planes flying overhead.

 

I use room correction EQ, and when doing measurements it can be surprising how those other noise sources interfere with getting a nice clean measurement of just the speakers.

 

Maybe someone will develop the noise cancelling headphone idea for an area as large as our listening rooms one day.

[firedog]

No, that sounds about right. My room is similar.

Don't forget that dB is a logorithmic scale so 30dB is twice as loud as 20. Every 10 db is a doubling of the loudness.

[bikeman]

No, that sounds about right. My room is similar.

Don't forget that dB is a logorithmic scale so 30dB is twice as loud as 20. Every 10 db is a doubling of the loudness.

 

Hmm...I thought approximately every 3dB is a doubling of loudness. 10dB = 1B which is actually 10 to the power of 1. So 10dB is 10 times louder.

[esldude]

Hmm...I thought approximately every 3dB is a doubling of loudness. 10dB = 1B which is actually 10 to the power of 1. So 10dB is 10 times louder.

 

I think what Firedog had in mind is that generally 10 db sounds twice as loud subjectively to humans. So yes, it terms of power it is 10 times. In terms of subjectively perceived level Firedog has it right.

[corehun]

Given all the recent posts about what we can and cannot hear, I wondered what noise floor my system actually had to overcome in my listening room. When I'm in that room with the system turned off, it seems totally silent, but using the SPL Meter in Studio Six's AudioTools and the internal microphone in my iPhone tells me that my "silence" is actually a level of background noise in the high 20's dB's. That seemed incredibly noisy until I read that a quiet bedroom at night is generally in the 30's and the background level in a TV studio is 20dB or so.

 

Do you know what yours is and have you attempted to do anything to lower it?

Hi,

 

Are you talking about dBa or dBc? The results could be quite different from each other... I think 30 db in c weighting is a quite good result...

[bikeman]

I think what Firedog had in mind is that generally 10 db sounds twice as loud subjectively to humans. So yes, it terms of power it is 10 times. In terms of subjectively perceived level Firedog has it right.

 

Fair enough. So, reproducing 10dB louder requires your amp to produce 10 times as much power (and your speakers to reproduce it), but subjectively sounds only twice as loud! I think this is why my system sounds better at night (25dB room noise floor compared to 35dB during daytime). I don't have to turn up the volume as much and this puts less demands on my amp/speaker, not to mention to the room itself. I used think "cleaner" AC power at night was the reason for better sound, but now I think it is really the lowered noise floor.

[senorx]

Assuming the free SPL app I downloaded is reasonably accurate and the mic on my tablet is too, I live in a noisy place, with a floor of around 70db without a fan on, 80db with fan on low, and 90db with fan on high. The fan is generally on 24/7/365, usually on low. For obvious reasons I mostly listen with headphones.

[Speedskater]

What budget SPL meters read anywhere near that low?

My old Radio Shack meter only goes down to 60dB full scale.

[bikeman]

What budget SPL meters read anywhere near that low?

My old Radio Shack meter only goes down to 60dB full scale.

 

Smartphone/Tablet apps such as "Decibel 10th" that use the built-in mic. I suspect they are not as accurate as dedicated devices such as the Radio Shack SPL meter in terms of absolute values, but I'm guessing they provide a reasonably good indication of relative values.

[esldude]

Fair enough. So, reproducing 10dB louder requires your amp to produce 10 times as much power (and your speakers to reproduce it), but subjectively sounds only twice as loud! I think this is why my system sounds better at night (25dB room noise floor compared to 35dB during daytime). I don't have to turn up the volume as much and this puts less demands on my amp/speaker, not to mention to the room itself. I used think "cleaner" AC power at night was the reason for better sound, but now I think it is really the lowered noise floor.

 

Yes, I have heard the old idea things sound better late at night because of cleaner power so many times, and my immediate response is the more likely explanation is the substantially lowered noise floor. Easier on your amp, and easier on your ears. People also forget at the higher sound levels somewhere around 85 db and above your ears themselves also begin distorting.

[esldude]

Assuming the free SPL app I downloaded is reasonably accurate and the mic on my tablet is too, I live in a noisy place, with a floor of around 70db without a fan on, 80db with fan on low, and 90db with fan on high. The fan is generally on 24/7/365, usually on low. For obvious reasons I mostly listen with headphones.

 

 

Now that would be an unusually NOISY PLACE TO LIVE!

 

Don't know which phone ecosystem you are in, but I would try some other apps.

[toddrhodes]

Smartphone/Tablet apps such as "Decibel 10th" that use the built-in mic. I suspect they are not as accurate as dedicated devices such as the Radio Shack SPL meter in terms of absolute values, but I'm guessing they provide a reasonably good indication of relative values.

 

I have an SPL meter but it only goes to a minimum of 40 dB so that won't work. I have a Dayton calibrated MIC and could load up REW, but instead I went with my phone and a free dB app. I wasn't looking for accuracy to a 10th of a dB, but I did want something that could tell me: Todd, your room is 50 dB now. <do some things> Now it's 40 dB, and so forth. So I just wanted to get an idea that I was making improvements.

 

And boy did I. My room is a room in the basement, furthest from the house mechanicals, enclosed, no ceiling but exposed Rockwool and "pink stuff" up there, normal drywall, acoustic treatments using OC703, and a standard laminate floor with an area rug on it. No glass in the room at all, and a curtain hung up to strategically limit corner reflections.

 

With the door closed, prior to any additional noise-killing work, I measured 28 dB, if memory serves. This was with no music playing, Amp/DAC/Pre turned on, PC on, and TV on (58" Plasma). The room is 11 x 13 roughly, so not very large.

 

After killing three fans in the PC (monitoring temps of course) including going to a silent PSU, turning off the TV, idling the CPU HSF to 900 RPM I am down to a scant 16dB. It actually flutters between 15 and 16 dB. It's flipping *quiet* in here, like with everything off you can hear every part of your breath, small movements in the chair, it's great, but almost eery in a way.

 

The improvement in sound by going from a 29dB noise floor to a 16dB noise floor was so significant, NO amount of investment in hardware, gadgets, or room treatments would beat it. It was incredible, all the low level detail that just pops out at you now. There's a part in Black Sabbath - Rat Salad where you can hear the drummer click his sticks together, there's a part at the end of Green Day - Letterbomb where, during the long sustain, you hear the band put their instruments down. It's a ton of fun listening in here, and isn't something I can even replicate on headphones though, to be fair, I use open cans in a noisy office.

 

Still, this is a great post, and again I'll reiterate - my room MIGHT NOT truly be a 15-16dB noise floor as the app is going through my phone and it was a freebie, but regardless, carving 13dB out of a room makes an enormous difference. If you want to debate how network and SATA cables, or playing from an SSD drive, or shutting down a service impacts sound; try starting with the big stuff first. It's easy to think "Well I can barely hear the noise, the music will drown it out anyway!" That's not remotely true.

[toddrhodes]

Since it had been awhile since my last measurement I decided to try it again. I also double-checked that I'm using C-weighting in the app, and I am. My wife is walking around upstairs so the numbers are jumping more than normal but as I last saw, with the TV on, I'm at about 18-19, off it's 15-16 unless something moves upstairs. I do most of my listening after everyone else is in bed and that was when I took the last measurements. I don't know that I could make it much quieter in here.

[senorx]

Now that would be an unusually NOISY PLACE TO LIVE!

 

Don't know which phone ecosystem you are in, but I would try some other apps.

Well, I have a 12 inch fan running 24 7 3 feet from my head, and a 30 inch 3 speed fan running 90% of the time 6 feet from my head on the other side, so it wouldn't surprise me if that was correct. My device is an android tablet, but it is a moot point anyway as I can't change any of these factors. I'll try some other apps, but my suspicion is that it is about right.

 

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[tranz]

Well, I have a 12 inch fan running 24 7 3 feet from my head, and a 30 inch 3 speed fan running 90% of the time 6 feet from my head on the other side, so it wouldn't surprise me if that was correct. My device is an android tablet, but it is a moot point anyway as I can't change any of these factors. I'll try some other apps, but my suspicion is that it is about right.

 

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Is this a Guantanamo bay torture room? I feel for you as that is unhealthy, hearing loss inducing levels. I do not even play my music that loudly. Perhaps try another measuring device.

[esldude]

Well, I have a 12 inch fan running 24 7 3 feet from my head, and a 30 inch 3 speed fan running 90% of the time 6 feet from my head on the other side, so it wouldn't surprise me if that was correct. My device is an android tablet, but it is a moot point anyway as I can't change any of these factors. I'll try some other apps, but my suspicion is that it is about right.

 

Sent from my SM-T700 using Tapatalk

 

Well it is possible, but that is loud enough to interfere with normal conversation.

 

Not knowing which app you have this may be a stupid question, but is your app showing perhaps -70 to -80 db relative to some maximum for the built in microphone? Some of the apps work this way.

 

One I have found pretty accurate on most Samsung phones is :

 

https://play.google.com/store/apps/details?id=com.pjw.noisemeter&hl=en

 

While I am at it, this is a good sort of real time spectrum analyzer called Frequensee:

 

https://play.google.com/store/apps/details?id=com.DanielBach.FrequenSee&hl=en

 

With this you will usually find phones and tablets start a roll off around 200 hz and often have little response below 100 hz. Or find something weird, like my Nexus tablet creating its own low level 10 khz idle tone.

[firedog]

Mine is about 35db with no heating and AC on, goes up to about 50 with it on.

[senorx]

Well it is possible, but that is loud enough to interfere with normal conversation.

 

Not knowing which app you have this may be a stupid question, but is your app showing perhaps -70 to -80 db relative to some maximum for the built in microphone? Some of the apps work this way.

 

One I have found pretty accurate on most Samsung phones is :

 

https://play.google.com/store/apps/details?id=com.pjw.noisemeter&hl=en

 

While I am at it, this is a good sort of real time spectrum analyzer called Frequensee:

 

https://play.google.com/store/apps/details?id=com.DanielBach.FrequenSee&hl=en

 

With this you will usually find phones and tablets start a roll off around 200 hz and often have little response below 100 hz. Or find something weird, like my Nexus tablet creating its own low level 10 khz idle tone.

 

Installed the "noisemeter" app you recommended (thanks) and it reads about 60db with the fan on low, which is better, assuming it is the more accurate app, but still kinda loud. I know I have to really crank it up with open headphones to not hear the noise.

[bluesman]

Every 10 db is a doubling of the loudness.

It's a doubling of perceived loudness (i.e. it sounds "twice as loud").

[bluesman]

I live in a noisy place, with a floor of around 70db without a fan on, 80db with fan on low, and 90db with fan on high.

That's really loud! OSHA set 90dbA TWA (time weighted average) years ago as the maximum permissible ambient SPL for an 8 hour exposure without ear protection. A continuous hearing conservation program is required by law in any workplace in which background SPLs reach a TWA of 85 dbA, and protective devices are required above 90. 80+ db ambient SPLs in a home would be incredibly loud and a risk for long term noise-induced hearing loss.

 

Interestingly, OSHA bases its hearing conservation programs on the concept of a sound "dose" and uses 5 db as the doubling factor. A TWA of 90 dbA for 8 hours is one dose (100%). 95 dbA is a 200% dose, etc. Permissible exposures and required actions in the workplace are based on the measured dose.

[senorx]

That's really loud! OSHA set 90dbA TWA (time weighted average) years ago as the maximum permissible ambient SPL for an 8 hour exposure without ear protection. A continuous hearing conservation program is required by law in any workplace in which background SPLs reach a TWA of 85 dbA, and protective devices are required above 90. 80+ db ambient SPLs in a home would be incredibly loud and a risk for long term noise-induced hearing loss.

 

Interestingly, OSHA bases its hearing conservation programs on the concept of a sound "dose" and uses 5 db as the doubling factor. A TWA of 90 dbA for 8 hours is one dose (100%). 95 dbA is a 200% dose, etc. Permissible exposures and required actions in the workplace are based on the measured dose.

Dennis actually posted a link for a different SPL app above, and it said 60 dB with my fan on low, so go figure.

 

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[Jud]

As with many Wednesdays, off from work today. Here at home during the day, using the AudioTools sound level graphing app with the iPhone 6 internal mic. Windows open, lots of birds singing, insects making various noises, etc. Average level is about 32-35dB A weighted, ~42-43dB C weighted, and a couple dB higher unweighted.

[NOMBEDES]

Oak.

[senorx]

Oak.

Lol

 

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